In the manufacture of punch press equipment, it is desirable to provide the punches and the dies with as much versatility as possible inasmuch as punch press operators are called upon to perform punching operations with a wide variety of shapes and sizes. The punch portion of a punch press may include a punch mount that is attached to the driving mechanism of the punch, a punch pad that is carried by the punch mount, and a punch tip that is mounted to the punch pad and which is receivable within a die of the same shape as the punch tip. During a punching operation in which a sheet of steel, for example, is being punched, the punch tip is driven through the sheet material and into the die, and then is rapidly retracted. As the punch tip is retracted, it tends to carry with it the sheet material; that is, it tends to lift the sheet stock away from the die. Stripper plates, of the type generally shown in U.S. Pat. No. 4,446,767 may be used to prevent the sheet material from following the punch tip as it is retracted (that is, "stripping" the sheet material from the punch tip), but this requires an extremely strong joint between the punch pad and the punch tip to continuously resist the pull that the sheet stock places on the punch tip. The punch tip must be very accurately oriented on the punch pad, of course, so that the punch tip fits exactly into the mating die during a punching operation to avoid equipment breakage or undue wear.
Once the desired punch shape has been determined, it would be desirable to have the capacity to readily manufacture a die, a punch tip, and a punch pad that carries the punch tip in precisely the correct orientation for use in a punching operation.
The inventors experience difficulty in attaching the punch tip to the punch pad in a manner that would both (a) accurately position the punch tip with respect to the punch pad within very narrow tolerances, and (b) fasten the punch tip to the punch pad with sufficient strength so that the punch tip would not come loose or be moved out of position during a punching operation. The inventors found, for example, that the punch tip could be silver soldered to a punch tip holding device such as a punch pad, and although the strength of the fastening operation appeared to be adequate, it was not possible to maintain the needed position accuracy of the punch tip with respect to the punch tip carrier.